JPS644362B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for constructing a hybrid circuit using coplanar lines on a semiconductor substrate.

(Prior art and problems) Figure 1 shows a conventional hybrid circuit.
A is a plan view, and b is a sectional view.

In a conventional hybrid circuit using coplanar lines, slot lines 5, 8, 9 and microstrip lines 6, 7, 10 are provided on one side of a dielectric substrate 13, as shown in FIG. The conductors 11 and 12 in through holes provided in the body substrate were used to connect the conductors 11 and 12 to each other.

In such a conventional structure, since both sides of the substrate are used, high precision is required for alignment between the pattern on the front surface and the pattern on the back surface, making the manufacturing process complicated. In addition, in order to connect the lines formed on the front and back sides, a through hole is provided in the board and a conductor is inserted inside this hole.
In such a structure, parasitic elements exist due to the influence of discontinuities, so that it can only be applied to frequency regions where the influence of parasitic elements can be ignored. That is,
In high frequency bands, the influence of parasitic elements increases,
Therefore, there is a drawback that there is a frequency limit to which this configuration can be applied. Further, when providing through holes in the substrate, machining and the like are required, and the entire circuit cannot be manufactured by patterning alone, resulting in an increase in manufacturing costs.

(Object of the Invention) In order to eliminate these drawbacks, the present invention constitutes a hybrid circuit using only coplanar lines on a semiconductor substrate, and will be described in detail below with reference to drawings of embodiments.

(Embodiment of the invention) FIG. 2 is a diagram showing an embodiment of the present invention,
This figure shows an embodiment according to claim 2, in which 1, 2, 3, and 4 are input/output ports, 15 is a slot line, 16, 17, and 18 are coplanar lines, 19 is a coupled slot line, 20,
21 and 22 are strip conductors, 23 is an insulating film, 1
4 represents a semiconductor substrate.

The input signal from port 1 passes through the slot line 15 and is converted to the coupled slot line 19. However, since the two outer conductors at the other end of the coupled slot line 19 are short-circuited by the strip conductor 22, the coupled slot line 19 is If the length is selected to be an odd multiple of a quarter wavelength, the input impedance on the coupled slot line side becomes infinite at the connection point between the slot line 15 and the coupled slot line 19, and the input signal is transferred to the coupled slot line side. It does not propagate to Therefore, the signal will propagate to the coplanar lines 16 and 17, but at this time the strip conductor 20
The signals applied to and 21 are in opposite phases to each other.

The operating principle of the embodiment will be explained below.
To facilitate understanding, the basic operation of the transmission line will first be described based on FIGS. 3 and 4.

FIG. 3 is a diagram showing a cross section of a coplanar line and a slot line, in which FIG. 3a shows a cross section of the coplanar line, and FIG. 3b shows a cross section of the slot line.

In the case of a coplanar line, the electric field distribution of electromagnetic waves propagating through the line is symmetrical as shown by arrows 26 in the figure, and is called an unbalanced mode. Therefore, a coplanar line is a type of unbalanced line.

On the other hand, the electromagnetic waves propagating through the slot line are
The electric field distribution is as shown by the arrow 26 in Figure b, and it is called a balanced mode because it propagates between two conductors like two balanced lines, and the slot line forms a balanced line.

FIG. 4 shows how the balanced mode propagating through the slot line 15 is converted to another line.

FIG. 4a shows a circuit in which the slot line 15 is connected to a coupled slot line 19. The signal from input port 27 propagates through slot line 15 and is split into two in series at connection point 29 of the combined slot line. The two-split signal propagates on the coupling slot line 19 in the direction of the electric field as shown by the arrow in the figure. The propagation mode of a coupled slot line with such an electric field direction is called an even mode.

That is, in the case of a cascade connection of a slot line and a coupled slot line as shown in FIG. 4a, the balanced mode of the slot line is coupled only to the even mode of the coupled slot line.

In Fig. 4b, the slot line is the coplanar line 16.
(The propagation mode corresponds to the odd mode of the coupled slot line).

The signal from the input port 27 is sent to the slot line 15.
is propagated and is divided into two in parallel via a strip conductor 20 connected to a coplanar line 16. The electric field distribution within the insulating film 23 on the lower surface of the strip conductor 20 is as shown in FIG. 4c, which is a cross-sectional view taken along line AA' in FIG. 4b.

The electric field of the signal divided into two in parallel has a symmetrical distribution with respect to the center conductor of the coplanar line 16.

That is, in a structure in which a slot line and a coplanar line are connected via a bridge as shown in FIG. 4b, the balanced mode of the slot line is coupled only to the unbalanced mode of the coplanar line (or the balanced mode of the combined slot line).

FIG. 5a is a diagram illustrating the operating principle of the embodiment shown in FIG. 2, in which the input signal from port 1 propagates through slot line 15,
is excited in an even mode and is short-circuited at the central portion 29 of the strip conductor 22. Since the electric field distribution within the insulating film 23 is in the opposite direction as shown in the figure,
This will provide an electrical short circuit condition.

The length of the coupled slot line 19 is selected to be an odd multiple of a quarter wavelength, so when it is short-circuited as shown in Figure 5a, the strip conductors 20, 2
1 and the coupling slot line 19 when looking at the coupling slot line side, the impedance becomes infinite.

Therefore, the input signal does not propagate to the coplanar line 18 side, but is coupled to the coplanar lines 16 and 17 (mode conversion shown in FIG. 4b), and is obtained from the output ports 2 and 3. The phases at this time are opposite phases.

Conversely, the input signal from port 4 passes through the coplanar line 18, excites the coupled slot line 19 in an odd mode, and propagates; however, since only the even mode is coupled to the slot line 15, it does not propagate, and is transmitted through the coplanar line 16. , 17 via strip conductors 20, 21, and outputs are obtained from output ports 2, 3. The phases at this time are in phase.

In this way, in the circuit shown in Figure 2, ports 1 and 4 are not coupled, and the input from each port is equally divided between ports 2 and 3, and the phases are the same (port 4 is the input port). The phase is reversed (port 1 is the input port), and this circuit operates as a 180° hybrid circuit.

Since the circuit with this configuration uses only one side of the board, the pattern can be fabricated by etching only one side.Furthermore, since the connection part between the coplanar line and the slot line is constructed with a multilayer structure, the circuit size can be reduced. I can do it. In addition, since no machining is required, circuits can be manufactured with high precision.
The value of parasitic elements in the line conversion section can be made sufficiently small.

FIG. 6 is a diagram showing another embodiment of the present invention, and corresponds to claim 1, in which 24 and 25 are slot lines. The circuit operation is similar to that shown in FIG. 2, which shows that a 180° hybrid circuit can be constructed without using a coupling slot line.

The one shown in Fig. 6 differs in that the part that was a combined slot line in the embodiment shown in Fig. 2 is now a two-slot line, but the other configuration etc. are the same as the one in Fig. 2. However, when used only at relatively low frequencies, since the two slot lines 24 and 25 are independent, it has the advantage of being easier to design than a system using coupled slot lines. .

(Effects of the Invention) As explained above, the coplanar hybrid circuit according to the present invention is constructed on a semiconductor substrate, and the connections between the coplanar lines, that is, the slot lines, the coupled slot lines, and the coplanar lines can be made without mechanical work. can be constructed on the same plane using only an etching process. In addition, since pattern dimensions can be specified with etching precision, unnecessary coupling between lines due to parasitic elements can be avoided even in high frequency bands, which has the advantage of dramatically extending the operating frequency range of the circuit. There is an advantage that highly functional circuits such as circuits can be constructed.

[Brief explanation of drawings]

Fig. 1 shows a conventional hybrid circuit, Fig. 2 shows an embodiment of the present invention, Fig. 3 shows a cross section of a coplanar line and a slot line, and Fig. 4 shows a cross section of a coplanar line and a slot line.
The figures show how the balanced mode propagating through the slot line is converted to other lines, and FIGS. 5 and 6 are views showing other embodiments of the present invention. 1, 2, 3, 4, 27, 28... Input/output port, 5, 8, 9, 15, 24, 25... Slot line, 6.7, 10... Microstrip line, 11, 12... ...Through hole inner conductor, 13...
Dielectric substrate, 14... Semiconductor substrate, 16, 17,
18... Coplanar line, 19... Coupled slot line, 20, 21, 22... Strip conductor, 2
3... Insulating film, 26... Direction of electric field, 29... Center portion of strip conductor 22.

Claims (1)

[Scope of Claims] 1. One end of two slot lines provided side by side on a semiconductor substrate is connected to another slot line, and this is used as a first connection point, and the slot line of the one line is The other end serves as a first input/output port, and the center conductor of the first and second coplanar lines is connected to the conductor located between the two slot lines installed side by side at the first connection point. The other ends of these first and second coplanar lines serve as second and third input/output ports, while a quarter of the center frequency is connected to the first connection point of the two slot lines installed side by side. 1
A third coplanar line is connected to a point at a distance corresponding to an odd multiple of the wavelength, and this is used as a second connection point, and the other end of the third coplanar line is formed as a fourth input/output port. A coplanar hybrid circuit characterized in that two outer conductors of the slot line are connected at a second connection point. 2. The coplanar hybrid circuit according to claim 1, wherein the two slot lines installed side by side are combined slot lines.